And I'm David Greene. Mitt Romney chalked up three more high-profile endorsements this week from opposite ends of the Republican ideological spectrum. This does add fuel to Romney's effort to paint himself as his party's inevitable candidate - ahead of next week's primaries in Wisconsin, Maryland and Washington, D.C. NPR's Wade Goodwyn has that report.

WADE GOODWYN, BYLINE: There's been growing recognition inside the Republican establishment that the primary is not doing great things for Mitt Romney's image. A CNN poll earlier this week had only 37 percent of those polled now with a favorable view of the former Massachusetts governor.

With an eye to building some momentum, yesterday former President George H. W. Bush, that's the first President Bush, endorsed Romney in his office in Houston.

PRESIDENT GEORGE BUSH: Well, I think it's time for the people to all get behind this good man. We're so convinced, and maybe because we've known Mitt for a long time, that he's the man to do this job and get on and win the presidency.

GOODWYN: It was a nice moment for Governor Romney, who was clearly appreciative.

MITT ROMNEY: Having your support means a great deal to me on a personal basis, a family basis, and also on a national basis.

GOODWYN: The former president's wife, Barbara, has already been working for Romney, recording robocalls for his campaign. And his son, former Florida Governor Jeb Bush, has also already endorsed Romney.

And Wednesday night, freshman Florida senator Marco Rubio came out for the frontrunner. Rubio expressed concern that if the race continued until the Republican convention, the eventual nominee would be too badly damaged.

SENATOR MARCO RUBIO: And I think that a floor fight in Tampa would be the worst possible thing we can do in terms of winning in November.

GOODWYN: And this morning, Romney added one more conservative voice to his roster of supporters â House Budget Committee Chairman Paul Ryan.